Hi,
I have BC and AC too. With AC I sometimes second-guess myself more than with BC, sometimes less.
More relaxed about some things because I have a lot more experience with children now than when I had my first. So can see things in perspective, allow AC to do things in their own time without worrying about things, etc.
On the other hand friends tell me I tend to over-analyse things regarding AC and remind me that not everything is necessarily (directly) related to AC's early experiences, or the fact of their adoption.
But it's hard isn't it? BC used to be very, very clingy, needing lots of attention; which made certain things hard (e.g. getting stuff done during the day) or unpleasant/pointless (e.g. going to a playgroup - I can sit on the floor playing with my child at home too). AC is comparatively 'easy' - happy to sit and watch, to play by themselves, to explore new toys by themselves at playgroup, and such. So... too easy? Do I enjoy the relative easiness, get stuff done, talk to other mums? (When I do, I feel guilty.) Or do I suspect attachment 'issues' and take action, increase my focus on activities that help attachment, keep AC close? (When I do that, I wonder if I am falsely attributing what is in fact normal character variation, to the adoption background; creating an issue where there is none?) Or is it something in between: Yes, attachment not as good as could be yet, but that is not a sign of 'issues' but merely an effect of relatively early days? Give it time, watch and see?
Could run around in circles forever!
I don't really have a solution, apart from easy to say, hard to do advice such as 'find your zen', be mindful, ... but I can say that I find it to have become easier, as time has passed. We are all settling into our new family life and with that, the fact of AC's adoption is becoming, hm, not forgotten or less important or meaningless, but, how to say... It is becoming our version of 'normal', I think. And that helps.
Good luck to you - I hope 'talking' about things helps a little!